Vehicles that have been designed to carry large cargo loads face unique operating conditions due to the circumstances that can be expected during use. For instance, the engines of heavy duty trucks, which include those trucks having a gross vehicle weight range of over about 9,000 kg (about 19,800 pounds), operate at high temperatures, particularly when carrying a load. In addition, heavy duty truck components will encounter high mechanical stresses, large vibrations, and environmental assaults (e.g., dirt and rocks, extreme heat and cold, chemical assaults, etc.) on a regular basis. The day-to-day operating conditions for a heavy duty truck are more extreme in almost every respect as compared to a typical passenger vehicle and the components used to form the heavy duty truck should provide the desired strength characteristics and resistance to degradation in the face of the expected operation conditions over the life of the vehicle.
In addition, cost and revenue associated with transport of goods are influenced by the weight and durability of the transport vehicles. Exemplary costs include fuel and maintenance. Each pound weight of a vehicle increases fuel consumption and wear on a vehicle. Revenue is also affected by weight. Each pound of additional cargo that may be transported leads to increased revenue. As such, transportation companies attempt to reduce the weight of vehicles while simultaneously retaining durability of replaced parts.
To reduce the weight of the vehicle, manufacturers of transportation vehicle parts have looked to reduce the weight associated with the parts. For example, many heavy duty truck components that have been formed in the past from metals have been examined for formation from lighter weight polymers. Many components such as hoses, belts, fuel lines, cooling system components, brake components, couplings, etc. are now formed to include the maximum amount of polymeric materials. Many of these components are currently formed of various synthetic rubbers, such as silicone rubbers. Unfortunately, these materials can exhibit less than desirable resistance to high temperatures as well as physical and chemical assaults expected in the harsh conditions of use.
Polyarylene sulfides are high-performance polymers that may withstand high thermal, chemical, and mechanical stresses and are beneficially utilized in a wide variety of applications. Polyarylene sulfides have often been blended with other polymers to improve characteristics of the product composition. For example, elastomeric impact modifiers have been found beneficial for improvement of the physical properties of a polyarylene sulfide composition.
Unfortunately, elastomeric polymers generally considered useful for impact modification are not compatible with polyarylene sulfides and phase separation has been a problem in forming compositions of the two. Attempts have been made to improve the composition formation, for instance through the utilization of compatibilizers. However, even upon such modifications, compositions including polyarylene sulfides in combination with impact modifying polymers still fail to provide product performance as desired, particularly in applications that require both high heat resistance and high impact resistance as may be encountered by heavy duty truck components.
What are needed in the art are heavy duty truck components formed of polyarylene sulfide compositions that exhibit light weight in conjunction with high strength characteristics and resistance to degradation, even in extreme operating conditions as may be expected for heavy duty trucks.